Metastable low energy states in TiS2, TiSe2, TiTe2 systems predicted with evolutionary algorithms

TL;DR

This study uses evolutionary algorithms and DFT to identify low energy metastable states in TiS2, TiSe2, and TiTe2, revealing differences among these van der Waals semimetals and suggesting a link to charge density wave phenomena.

Contribution

It is the first systematic computational investigation of metastable states in these materials using evolutionary algorithms combined with DFT.

Findings

Multiple metastable states found in TiSe2 and TiS2

No low energy metastable states in TiTe2

Some metastable states identified as charge density waves

Abstract

We report a systematic study of low energy metastable states in van der Waals semimetals TiS2, TiSe2 and TiTe2 within the DFT theory by means the evolutionary search algorithm. We find a big difference between TiSe2, TiS2 and TiTe2 in low energy metastable states. While several metastable states exist in TiSe2 and TiS2, no low energy metastable states were found in TiTe2. We show that some of the obtained metastable states can be identified as charge density wave (CDW). We argue that existence of the low energy metastable phases indicates that emergence CDW as a ground state in these compounds.